Buffing machine



Oct. 5, 1937. e; E. MCLAUGHLIN ET'AL BUFFING MACHINE Filed June 5, 1936 Patented Oct. 5, 1937 7 UNITED STATES FATENT OFFICE.

BUFFIN G MACHINE Application June 5, 1936, Serial No. 83,718

9 Claims.

This invention relates to surfacing rolls for operations upon hides, skins and leather. While the invention is illustrated with reference to a roll designed for buffing leather surfaces, it will 5 be understood that the invention and various important features thereof may'have other applications and uses.

As heretofore constructed, surfacing rolls intended to operate economically in the buffing of leather surfaces have been constructed as abrasive cylinders of considerable length in which the abrasive material was formed integrally with the surface portions of the cylinder or, alternatively, was carried by sheet material wound spirally about the surface of the cylinder, the arrangement being such as to operate at any given instant upon extensive portions of the piece of work undergoing treatment. In those cylinders which are formed with abrasive material embedded in the surface of the cylinder, inequalities commonly develop in the surface of the cylinder due to unequal wear. It follows that the cylinder must be subjected at intervals to a truing operation which requires both time and special equipment to produce satisfactory results. In a cylinder covered with'a spirally wound abrasive sheet, considerable difficulty is experienced in securing the abrasive sheet in place and in maintaining it at the desired tension. Furthermore, with such relatively long edge portions exposed to the hazard of injury in buffing operations upon material which varies greatly in its qualities and in the unevenness of the surface presented for treatment, there is a disadvantage which becomes marked whenever a portion of such edge of the abrasive sheet becomes torn or unduly worn. The difficulties referred to are encountered in securing abrasive sheet material in properly tensioned condition upon the surfaces of cylinders of, for example, more than a foot in length, and in maintaining proper tension' during the life of the abrasive sheet covering such' cylinders.

It is an object of this invention to facilitate the attachment of abrasive sheet material properly tensioned upon the surfaces of relatively long cylinders, without winding it spirally about the cylindrical surfaces as heretofore. It is a further object of the invention to provide simple, efiicient, and readily operable means for the pur- 50 pose mentioned.

To these ends, and in accordance with an important feature of the invention, there is provided, in conjunction with a hollow bufiing'cylinder having. a slot, extending through the cylindrical Wall or shell of the cylinder in a plane at 5 an angle to the axis of the cylinder, to receive the ends of the abrasive sheet on the'surface of the cylinder, improved sheet-clamping devices inside of the cylinder arrangedv at an angle of less than 180 to each other substantially in a plane defined by said slot in the cylinder shell, the arrangement being such as to secure proper tension of the abrasive sheet upon the surface of the buifing cylinder and at the same time to reduce to a practical minimum the liability of injury to the abrasive sheet in securing and maintaining such proper tension.

In a practical device, the novel clamping means may comprise two rods slotted to receive end portions of an abrasive sheet embracing the cylinder and extended through the described slot in the surface of the cylinder in an arrangement wherein the said two slotted rods are angularly positioned end to end with respect to each other and independently operable to exert the required tension on the said abrasive sheet. By adjustment of first one and then the other clamping rod, from opposite ends of the bufiing roll, the abrasive sheet may be adjusted satisfactorily by one worker provided he exercises the required skill and care in the matter. Since this arrangement requires individual adjustment of the two clamping rods, it may be preferable to provide a coupling block positioned in hollowed-out por ticns of the adjacent ends of two or more angularly related clamping rods to secure simultaneous rotary movement of the rods through proper manipulation of a tool applied to the outer end of one of said rods. In this way adjustment may be more rapidly efiected, although the skilled operator may require assistance particularly where the abrasive sheet is quite wide. In another embodiment of the invention, two or more angularly related clamping rods may be connected to each other through flexible members joining the adjacent ends of any two angularly related clamping rods, said flexible portion beingalso slotted so that the slots in the clamping devices extend the full width of the abrasive sheet material, thus making it unnecessaryto notch theends of the abrasive sheet material as in those cases where, the slots in the clamping rods are not continuous one with the other.

' These and other important features of the invention and novel combinations of parts will now be described in detail in the specification and'then pointed out more particularly in the appended claims. 7 7

In the drawing, Fig. 111s aplan view of 'a buffing roll or cylinder; V Fig. 2791s a sectionalview taken along the line II -II of Fig. 1;

j Fig. 3 is a sectional view taken along thelline Fig. 4 isa sectional view taken along the line IV-IV of Fig. 1;

Fig. 5 shows diagrammatically the relative positions'of the ends of the clamping rods within the V Fig. dis a sectional view taken along the line VIVI of Fig. 2;

Fig. 7 is a sectional view taken along the line VIIVII of Fig.9;

Fig. 8 is a view similar to Fig. 2 showing another arrangement of clamping rods; Fig. 9 is'another viewsimilar to Fig. 2 and showing still another embodiment of the clamping means for the abrasive sheet material on the surface of the buffing cylinder; r

Fig. 10 is a detail view of a combined tightener and automatic slack takeup for the clamping rods; Fig. 11 is a detail view of a coupling block; and Fig. 12 is a detail sectional view showing the ends of the abrasive sheet material engaged in a clamping device. 7 r

In a preferredembodiment'of the invention, specially designed to operate upon tanned hides I or skins, there is provided a bufiing roll I4 of that type wherein the abrasive surface is provided by a sheet of abrasive material I5 (Fig.4) wrapped around the roll and secured thereto by having its ends passed through an inclined slot in the cylin- V drical'wall of the roll and into engagement with clamping. means 7 constructed and. arranged to maintainthe abrasive sheet material properly tensionedupon the cylindrical surface of a layer of felt 2| (Fig- 4) on the roll l4. As shown most I clearly in Fig. 1 of'the drawing, the roll, I4 is provided with a slot 22 through the cylindrical Wall or shell of the hollow roll, said slot being made by means of a plane cutter moved along a plane intersecting the cylinder at an angle to its supporting shaft 24. The relationship'of the slot .22.with respect to the shaft 24 is made clear by Fig. 4 wherein there is clearly indicated the angularity of the plane of the slot 22 to a plane defined by-theaxis of the shaft 24'and by a point in the center line of a clamping rod 28 for holding said abrasive sheet l5. Mounted in line with the slot 22is a pair of such clamping rods 26 and 28. While, in Fig. 2, the clamping rods are shown in a position to disclose the longitudinal slots 36 which receive'bothends of-the abrasive sheet material 15 passed through the slot 22, it will be understood that normally theseslots 30 will" be initially positioned in line with; that is, in the same planewith, the slot 22, to receive the ends of the sheet material I5, in which case the slots 3El'would not be seen in Fig.2. The clamping rods 26 and 28 are arranged end to end at an angle to each other 7 in the'plane of the slot 22, this angular relationship being'determined by the fact that the ends of the iods'26 and 28 are'all located in bearings equidistant from the surface of the cylindrical wall or shell of the roll {4. In other Words, the 7 bearings. at 32, 34 and for the ends of the rods the latter in such manner thatsaid ends are equally spaced from the inner surface of the shell of the roll l4, as indicated diagrammatically in. Fig. 5/ It is to be understood that'the ends of the rods 26; 28 need not abut each other. Furthermore, the adjacent ends of' the tworods may be. displaced somewhat laterally of each other without departing from the principle of this invention. It is to be noted that the equidistant spacing refers only to the ends of the rods, itbeing obvious 7 26 and 28, in theillustrated construction, support that the middle portion of each rod is spaced from v the adjacent inner surface of the roll- M a greater distance than said ends of the rods, since the rods are chords of 'anellipse. It will be readily under-,

stood that difierences in the spacing of various: portions .of the clamping rod with respect to adjacent points on the inner cylindrical surface of 'the roll M are minimized by subdividing the clamping rod and providing uniformly spaced bearings for the ends of said subdivisions of the rod upon the inner cylindrical surface of the roll I i, in marked contrast to the wide spacing of the central portion of a single rod extending the full length of the slot 22 in the roll 14. Furthermore, short rods of the same diameteras a single long rod will bend in the middle portions thereof, when placed under tension by the abrasive sheet material, substantially less than'a single long rod; 7

Hence, there is much less likelihood of. tearing the abrasive sheet material while tensioning the same on the surface of the roll or subsequently during operation of theroll upon pieces of Work. It is to be understood that a single clamping rod may be advantageously utilized in bufllng rolls of twelve 3 inches in length. In longer rolls, theillustrated construction has distinct advantages as pointed out above. In a buffing roll twenty-four inches in length, with a slot of the inclination indicated, a single rod of the weight indicated would be impractical since it would bend too much. The illustrated roll is twenty-four inches in length and about eleven inches in diameter and has a slot of an inclination such as to eliminate from the practical standpoint the bumping effect so noticeable in rolls with slots of much less inclination.

Conveniently thebearing 32 may be completely circular, as shown in Fig. 3, since the clamping rod 26 may be introduced into position in its bearings by being threaded through both bearings 34 and 32, a washer 38 being threaded upon the reduced end of the rod before it is thrust into the bearing 32. However, the bearing 36 is open at its lower portion, as shown in Fig. 6, to permit introduction of the clamping rod 28 into the bearing 35 by a swinging movement of the clamping rod 28 after the inner end of the latter has been introduced into the bearingi l. As indicated in both Figs. 2 and 6, the outer surface of the bearing 36 is provided with a circular recess adapted to receive a correspondingly shaped portion on the inner surface of a clamping nut Gil.

even tension on the abrasive sheet material throughout the width thereof on the roll l4. However, by this arrangement one workman can do the job of placing a fresh abrasive sheet on the buffing roll. In order to reduce the number of steps in adjusting the tension of the abrasive sheet material, there is provided a construction in which the two clamping rods are connected for rotation together while at the same time permitting the angular relationship of the rods, as described in the preceding paragraph. A construction with this purpose in mind is shown in Figs. 8 and 11 wherein the inner ends of clamping rods 42 and 44 are provided with sockets to receive a dumb-bell-shaped coupling member 46. If the .coupling member be roughly quadrilateral (as shown) the said sockets will be substantially rectangular in cross section, while if the coupling member be hexagonal in shape the sockets will be correspondingly shaped. It will be clear that this coupling provides a universal joint which constrains the two clamping rods 42 and 44 to rotate together while at the same time permitting maintenance of the angular relationship mentioned. Since the slots 3!) in the pairs of clamping rods 26 and 28 of Fig. 2 and 42 and 44 of Fig. 8 are in spaced relation at their inner ends, it is clear that both ends of the abrasive sheet material on the cylindrical surface of the roll I4 must be notched at the centers of said ends to provide for clearance of the bearing 34 while the said ends of the abrasive sheet material are being introduced into the slots 30 which at the time are in the plane of the slot 22 in the cylindrical wall or shell of the roll 14. To minimize strain on the material around the notch, the latter is rounded in shape. After the introduction of the ends of the sheet material, as described, the clamping rods are rotated to secure the abrasive sheet material in place in properly tensioned condition upon the surface of the roll To avoid the necessity of notching the ends of the abrasive sheet material on the surface of the roll !4 there may be provided, as shown in Fig. 9, a pair of clamping rods 48 and 50 in which their adjacent ends are connected by flexible members 52, 54 covered by flexible rubber composition so as to be of the same shape in cross section as the remainder of the slotted portions of the clamping rods 48 and 59, as indicated in Figs. 4 and '7. In this latter case, the slots in the clamping rods 48 and 5!] become continuous with each other, as clearly shown in Fig. 9. To permit rolling of the sheet material about the surfaces of the flexible members 52 and 54 there is provided a bearing 56 which is substantially larger than the cross sectional area of the two spaced members 52 and 54 so that the paper helps to fill the bearing, as it is wound upon the clamping rod of Fig. 9 which is, in effect, a single clamping rod. It is understood that the flexible members 52 and 54 permit the angular relationship described in connection with clamping rods 26 and 28 of Fig. 2 while, at the same time, constraining the two rods 48 and 5!] to rotate as a single rod.

As indicated in a preceding portion of this specification, the slot 22 in the roll Id is in a plane at an angle to the axis of rotation of the bufling roll, the purpose being to eliminate as much as possible a bumping effect that is commonly produced each time that a slot in the cylindrical surface of a buffing roll comes oppositeltoithe work backing portion of a work supporting roll during treatment of apiece of work, it being a well-known fact that there is a noticeable bumping effect in the operation of thosebuffing rolls which are provided with a slot parallel with the axis of rotation of theroll. Furthermore, a slot inclined in the manner shown in the drawing is more likely to produce uniform 'efiects on the surface of the work piece being treated than a buifing roll provided with slot of the other type mentioned.

Conveniently, means may be provided to op erate as an'auto'rnatic takeup to prevent any slack in the abrasive sheet on the surface of the bufiing roll, the construction being preferably such that spring means forming part of said automatic takeup: may be manually adjusted as to tension. Fig. 10 shows such a takeup applied to the clamping rod 28, which has keyed to one end a quill 69, said quill having integrally formed therewith a collar portion 62. Asshown, the quill t0, through being keyed to the clamping bar 28, must rotate with the latter but may slide longitudinally thereof. The quill 60 is rotatably mounted in a bearing 53 such as that shown at.

32 (Fig. 3), and not in a slotted bearing of the type shown in 6. It is to be understood that the automatic takeup may be applied to the outer ends of both clamping rods in Fig. 2 and to'the right end of each clamping rod in Figs. 8 and 9.

As shown, a spring 64 is wound upon the quill 5i! and has one end secured to the bearing 63 and its other end secured to a collar 66 mounted upon the end of the quill 6!! and adapted to be secured thereto by a gib screw 68.. Vihen it is desired toadjust the tension of the spring 64, the gib screw 58 is removed thus freeing the collar 65 for rotation upon the quill 65!. To tension the spring 6d the ends of the abrasive sheet material must first be inserted in the slots of the clamping rods and the latter adjusted to tighten the sheet. Then the collar 66 is rotated in a counterclockwise direction (when looking toward the right end of the. construction in Fig; 10) the. spring being maintained at the desired tension by reinserting the gib screw 68 in any one of a num ber of screw threaded openings Iii, two of which are shown in Fig. 10. After this preliminary tensioning of the spring 5 a socket wrench, having a part to enter a square socket in the end of the clamping rod 28, is utilized to rotate said clamping rod to tension still further the abrasive sheet which has been introduced into the slots 39. It will be noted in this connection that the cooperating teeth on the collar 62 and on the bearing 63 are pointing in a direction that permits them to slip over each other during rotation of the quill 66 and rod 23 in clockwise direction, the spring fi itending constantly to keep the two sets of teeth in engagement. Subsequently the nut 12 is screwed to position upon the end of the rod 28, the nut 52 and a pin M being provided to prevent the clamp rod from moving axially the bearing 53. It will be understood that the spring 64 tends constantly to rotate the clamping rod 28 in a clockwise direction thereby to maintain tension on the abrasive sheet and to tend constantly to take up any slack therein. The operation of the automatic takeup is of such a character that the members of the takeup, including the clamping rods, function without changing their center of gravity and therefore do not upset the. delicate balance of the highly rotative abra- I sive cylinder. Having described our invention, what we claim as new'and desire to secure by Letters Patent of the United St'ates'is:

1 In a bufiing machine, a hol1ow circular'cylinder, of uniform diameter adapted-to have a sheetof abrasive material securedupon its cylindrical surface through a slot extending throughthe shell of the cylinder in a plane at an angle to its axis of rotation, the length of said cylinder being substantially greater than its diameter, and. clamping devices for the ends of the abrasive sheet on the surface of the cylinder, said clamping devices comprising two rods mounted for'rotation about their-longitudinal axes and arranged at an angle of less than 180 to each other inga plane defined by said slot in'the shell of the cylinder.

2. In a buffing machine, a hollow circular cylinder of uniform diameter adapted'to have a for the ends of the abrasive sheet-on. the surfaceof the'cylinden-said'clamping devices being arranged at an angle of less than 180"t'o eaohf, other i'n'a plane defined by said slotgin the shell of the cylinder, and supports "f or the" ends of each of said clamping devices constructed," and arranged to maintain" the ends of 'each' ofthe clamping devices uniformly spaced at all times from the inner surface of said shell.

3; In a buffing machine, a hollow circular cylinder of uniform diameter adapted to have a sheet of abrasive material secured upon its cylindrical surface'through a slot extending through the shell ofthe' cylinder in a plane at an angle to its axis of rotation, said cylinder being greater than one foot in length, clamping devices for the ends of the abrasive sheet on the surface of the cylinder, said clamping devices being mounted for rotation about their longitudinal axes and arranged-end to end in a plane defined by said slot in the shellof the cylinder, and supports for the ends of said cl'ampin'g devices secured to the inner surface of said shell, 'said supports'being constructed and arranged to maintainthe ends of the clamping devices at, all times uniformly spaced from the inner surface of said shell;

4. In a bufling machine, a hollow cylinder adaptedto have a sheet of abrasive material secured upon itscylindrical surface through a slot extending through the shell of the cylinder in a plane at an angle to its axis'of rotation, and a clamping device for the ends of the abrasive sheet on the surface of the cylinder, said clamping device comprising two slotted rods mounted'for rotation about theirlongitudinalaxes and arranged end to end at an angle of less than 180 to each other in a plane defined by the slot in the shell of said cylinder.

5. In a buffing machine, a hollow cylinder adapted to; have a sheet of abrasive material secured upon its cylindrical surface through a slot extending through the shell of the cylinder in a plane at an angle to its axis of rotation, and a clamping. device for the ends of the abrasive sheet on the surface of the cylinder, said clamping device comprising two rods located below and in line with said slot and arranged "at an angle of less than 180 to each other in a plane defined by said'slot, said rods being rotatably supported at their 'ends by hearing members secured to and equally spaced from the inner'surface of the shell of the cylinder.

6. In a buffing machine, a hollow cylinder adapted to have a sheet of abrasive material secured upon its cylindrical surface throughla'slot extending through the'shell of the cylinder in'a plane at an angle to its axis of rotation, a clamp ing device for the ends of the abrasive sheet on thesurface of the cylinder, said clampingdevice comprising two slotted rods arranged at an angle of less than 180 to each other in a plane defined by the slot in the'shell of said cylinder, theadjacent ends of said rods having polygonally shaped sockets therein, anda coupling member disposed in said sockets to insure simultaneous rotative movement of the clamping rods;- I '7. In a buiiing machine, a hollow cylinder adapted to-have asheet of abrasive material secured upon its cylindrical surface through a slot extending through the'shell offthe cylinder in a plane at an angle to its axisof rotation, a clamping device for the ends'of theabrasive sheet on ,thesurf a ce of the cylinder,;sa id:clampingdevice comprisingtvvo slotted rods arranged at an angle .r 'off' less than 180 to each-other ma plane defined by the slot in the shell of said cylinder, and a r flexible connection between the adjacent ends of the clamping rods so that rotative movement of one rod causes corresponding movement of the other rod, said flexible connection being slotted throughout its length whereby-a continuous slot is provided in the clamping'device to receive the full width of the abrasive sheet on the surface of r the cylinder;

8. In a bufiing machine, ahollow cylinder adapted to have a sheet of abrasive material secured upon its cylindrical surfa'ce through a slot extending through the shell of the cylinder in a plane at an angle to its axis of rotation,'-a clamping device for-the ends of the abrasive sheet on the surface of the cylinder, said clamping'device comprising two rods mounted for rotation about of less than 180 to each other in a plane defined by said slot in the shell, and av universal joint connection between said rods at their adjacent .ing device for the ends of the abrasive sheeton the surface of the cylinder,- said clamping device comprising two slotted rods rotatably mounted and arranged at an angle of less thanl to each other in a plane defined by the slot in the their longitudinal axes and arranged at an angle shell of said cylinder, and spring operated take- 9 up means connectedto one or bothrods and tending constantly to rotate said rod or rods thereby to keep the abrasive sheet material under continuous tension.

GEORGE E. MCLAUGHLIN. WINN E. BROUGHTON. 

